Investigation of Separation Control by Boundary Layer Suction applied to a Highly-Loaded Axial Compressor Cascade

Computational method has been used to increase the physical understanding of the separation control by boundary layer suction in a highly-loaded axial compressor cascade. The investigated cascade in current paper has separations both on the suction surface (SS) along the whole blade span and three-dimensional separation in the hub corner. The results show that the flow structure can be changed after the suction, which leads to the variation of loss and blockage generation. The suction scheme on the SS can effectively control the boundary layer separation near trailing edge and to some extent mitigate the three-dimensional separation. The displacement thickness of the three-dimensional separation cannot be simply used to evaluate the overall performance due to the existence of the boundary layer separation on the SS, the variation of the flow pattern and vortex structures should also be considered. The effectiveness and mechanisms varies by conducting suction control at different development stage of the secondary flow. Applying suction control is suitable at the early development stage, and the earlier the better, while it is inappropriate to carry out the control at the middle development stage. The suction control at the late development stage is another relative effective method.